After politicians in Greece failed to agree on a coalition government, President Karolos Papoulias called for all parties to meet Wednesday to set up a caretaker government that will conduct new elections. The instability in Athens raised questions as to whether the country would be forced to leave the eurozone and what such a move would mean for other troubled European economies.

"Greece will hold fresh elections in June, negotiations to form a government based on this month's election results having officially failed," wrote Investec analysts Elisabeth Afseth and Brian Barry. "It should come as no surprise, but markets nevertheless took a turn for the worse on the announcement."

Shares of retailer JC Penney (JCP, Fortune 500) tumbled 15% in premarket trading, after it reported a much bigger than expected 39 cent a share loss for the most recent quarter -- far worse than the 11 cent loss forecast by analysts surveyed by Thomson Reuters, or the 30 cents a share profit it made a year earlier. The company also discontinued its dividend.

Office supply company Staples (SPLS, Fortune 500) reported earnings of 30 cents per share, excluding a 3 cent a share charge for staff cuts. That's up from 28 cents a share a year earlier, and matched analysts' forecasts. Still shares slipped 2.6% in premarket trading on an unexpected 1% drop in revenue.

Shares of Deere & Co. (DE, Fortune 500) rose 1.5% in premarket, after the company beat expectations on its quarterly results and raised its forecast. The company reported earnings of $2.61 per share, compared to the consensus expectations of $2.54, and boosted its full-year earnings forecast to $3.35 billion.

Target Corp. (TGT, Fortune 500)also beat expectations and increased its forecast, pushing shares up by 2% ahead of the bell Wednesday. The company reported earnings of $1.04 per share, compared to the consensus expectations of $1.01. The company raised its full-year guidance by 5 cents, to an adjusted EPS range of $4.60 to $4.80.

JPMorgan Chase (JPM, Fortune 500) shares edged higher Tuesday as the bank held its annual shareholder meeting in Tampa, Fla. The stock is down more than 12% over the previous five trading sessions, but shares rose 1.4% in premarket trading on Wednesday.

Shareholders approved pay packages for the bank's top executive, and affirmed their wishes to keep Jamie Dimon in the dual role of chairman and CEO.

The investment fund now holds holds roughly 10 million shares in General Motors and 1.6 million shares of Viacom. Shares of GM climbed 3.7% in premarket trading on the news, while Viacom shares edged up 0.7%. GM rival Ford Motor (F, Fortune 500) also gained 1.5% in premarket trading on Buffett's vote of confidence in the auto sector.